1. Field of the Invention
The present invention relates to inspection and review of substrates, such as, for example, semiconductor wafers and reticles for lithography.
2. Description of the Background Art
In a conventional electron beam (e-beam) inspection instrument, a manufactured substrate (such as a silicon wafer or a reticle) is scanned with a focused beam of electrons which results in the emission of secondary electrons from the substrate surface. The emitted electrons are detected, and the detection data is typically converted into images of the surface of the specimen. These images are then analyzed numerically to detect abnormalities (referred to as defects) in the manufactured substrate. The detected defects may be subsequently reviewed by further imaging.
The detected defects may also be classified, either manually or automatically, into different classes or categories. The classification of a defect may be used to determine its cause such that appropriate adjustments may be made in the manufacturing process so as to improve its yield.
It is highly desirable to improve methods and apparatus for the detection and classification of defects imaged by electron beam instrumentation.